This invention relates generally to an apparatus and a method for displaying a motion picture film on a television receiver, and in particular provides apparatus and a method for displaying a continuously moving film strip on a standard commercial television receiver.
Equipment has long been available which enables a commercial television station to broadcast a motion picture film in either color or black and white in a format compatible for reception on the standard commercial home television receiver. The cost of this capability is high however, in terms of both the capital required for the equipment and the complexity of the synchronizing and scanning devices used.
The commercial systems typically broadcast motion picture film projected at a rate of twenty-four frames per second on a home television receiver having a raster scan rate of thirty complete frames (or sixty half-frame fields) per second. Conversion of the film frame rate to the television frame rate is achieved by scanning successive film frames different numbers of times. Thus, the conventional commercial equipment first scans one film frame twice and displays the film scans in two consecutive television fields. The equipment then scans the next film frame three times and displays those three scans in the next three television fields. The sequence then repeats for the next two film frames. Thus, the commercial equipment displays each pair of two successive film frames in five consecutive television fields. The specific equipment used in this approach, such as the flying spot scanner which has a moving spot-like illumination source, are discussed in more detail in "Television Engineering Handbook", edited by Donald J. Fink and published in 1957 by the McGraw-Hill Book Company, Inc.
A conventional commercial system of the foregoing type is relatively inflexible. More flexible and electronically simpler systems have been described (for example, in Biber, U.S. Pat. No. 3,952,328, issued Apr. 20, 1976) which display a motion picture film, advancing at an arbitrary frame rate, on a color television receiver by coupling the display apparatus directly to the television receiver. In this system, the display apparatus provides both vertical and horizontal deflection signals to the television receiver, so that the receiver is "slaved" to the display apparatus and hence to the film scanning apparatus. While this system is commercially acceptable, it requires modification of the electrical circuitry of the standard television receiver. Hence it is not a consumer item with wide market appeal, even for a typical amateur photographer of movie films.
The amateur photographer has nevertheless considered his home television receiver as a logical display mechanism for motion pictures and in particular home movies. However, low cost equipment for displaying motion pictures on a standard television receiver is not available.
It is therefore a principal object of this invention to provide a method and apparatus for displaying a motion picture on an unmodified standard television receiver. Other objects of the invention are to provide a method and apparatus which are simple in operation, reliable, and relatively low in cost. Further objects of the invention are to provide such apparatus which uses a relatively small number of storage devices, thereby maintaining low cost and, further, in which the film and the associated drive mechanism are the only moving elements.